Lecture 2 Measurements Concentration Solution Preparation

Density kg/L = g/mL Density of o C 1.00 g/mL Specific gravity = density /(density of o C) Dimensionless! For diluted aqueous solutions, 1 kg  1 L Solutions

% ‘per cent’ 10g/1000g or 10g/L ppm ‘part per million’ /1,000, g/kg (10 -6 g = 1  g) 1  g/g or 1 mg/L 1  g/mL 1 mg/kg ppb ‘part per billion’ (10 -9 g = 1 ng) 1 ng/g or 1  g/L 1 ng/mL 1  g/kg ppt - parts per thousand or parts per trillion!?

Molarity mole/L Molecular mass, formula mass. Molecular weight, formula weight FWgrams! Molarity  10  (X %) / FW Example: 1% HCl FW = =36.5 Molarity(1%HCl)= 10/36.5=0.27 M Molarity =  (X ppm) / FW Example: 10 ppm Pb FW=207.2 Molarity(10ppm Pb)=  10/207.2=4.82  M In diluted aqueous solutions:

Dilution 10 mL  200 ppm = 200 mL  10 ppm To make 200 mL of 10 ppm solution from 200 ppm, take 10 mL and dilute to the volume of 200 mL 5 mL  M = 100 mL  M To make 100 mL of 0.02M solution from 0.40 M, take 5 mL and dilute to the volume of 100 mL C 1  V 1 = C 2  V 2